Positron emission tomography (PET) allows us to obtain anatomical data (e.g., axial transverse, coronal or sagittal images of the brain) as well as dynamic functional data (such as regional cerebral glucose consumption rate, using 18F-2-deoxyglucose (FDG). Besides FDG, other radiopharmaceuticals (tagged with 18F, 15O, 11C, 13N) can be used with PET to study the blood-brain barrier (BBB), oxygen metabolism, protein synthesis, and neuroreceptors. The unique property of PET is that it provides physiologic and pathophysiologic information not available with any other imaging procedure.